ISOLATION CELL USED AS AN INTERFACE FROM A CIRCUIT PORTION OPERABLE IN A POWER-DOWN MODE TO A CIRCUIT PORTION IN A POWER-UP MODE

摘要

An isolation cell provided between a first module (which can operate in either a power-up mode or a power down mode) and a second module. According to an aspect of the present invention, the isolation cell can be located to operate drawing power from either the first module or the second module without a floating node in the power-down mode of the first module. Due to the absence of the floating nodes, unneeded power drain is reduced/avoided. In one embodiment, a switch operates to connect power to a series of pair of inverters (propagating the signal from the first module to the second module) when the first module is in power-up mode and disconnects the power in the power-down mode.